今天继续给大家分享Error building SqlSession 之
The error occurred while processing mapper_resultMap[studentMap]。
当然了，前提是：
1、你已经把相应的映射关系给配置好了
2、和原接口同一包内的配置文件（我的工程是stuMpper）也配置到了主Mapper（我的工程是SqlMapper）中
3、当然了，相应的pojo和会话的执行语句也没有问题，这感觉已经配置的差不多了，但是会出现下面这个问题。
这是什么情况呢？我们看一下第二行，先找到出错位置：
The error may exist in com/zzxtit/boot/mybatis/mapper/stuMapper.xml
看样子是我的stuMapper配错了，再往下看就发现了具体的问题，说是处理这个resultMap时遇到了问题，当然我必须要看一下我再stuMapper中配置的这个映射有没有问题
看了一眼，显然没有，然后接下来就继续看下面的提示。
大家注意这一句：Could not resolve type alias 'student'.
这是什么意思呢？
很明显，我们再写完pojo之后并没有对他再Mapper中进行配置，那没有配置，怎么可以找到这个类呢？所以我们引用 <typeAliases> </typeAliases>标签把这个pojo给配置到Mapper中（我的是SqlMapper）：
<typeAliases>
<typeAlias alias="student" type="com.zzxtit.boot.mybatis.first.Student"/>
</typeAliases>完成了这一步，我们再进行junit测试，发现果然好用了。
在下面附上我们的事故现场：
org.apache.ibatis.exceptions.PersistenceException:
### Error building SqlSession.
### The error may exist in com/zzxtit/boot/mybatis/mapper/stuMapper.xml
### The error occurred while processing mapper_resultMap[studentMap]
### Cause: org.apache.ibatis.builder.BuilderException: Error parsing SQL Mapper Configuration. Cause: org.apache.ibatis.builder.BuilderException: Error parsing Mapper XML. The XML location is 'com/zzxtit/boot/mybatis/mapper/stuMapper.xml'. Cause: org.apache.ibatis.builder.BuilderException: Error resolving class. Cause: org.apache.ibatis.type.TypeException: Could not resolve type alias 'student'. Cause: java.lang.ClassNotFoundException: Cannot find class: student
at org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:30)
at org.apache.ibatis.session.SqlSessionFactoryBuilder.build(SqlSessionFactoryBuilder.java:80)
at org.apache.ibatis.session.SqlSessionFactoryBuilder.build(SqlSessionFactoryBuilder.java:64)
at com.zzxtit.boot.mybatis.mapper.MapperDemo.init(MapperDemo.java:27)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:24)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:86)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:538)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:760)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:460)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:206)
Caused by: org.apache.ibatis.builder.BuilderException: Error parsing SQL Mapper Configuration. Cause: org.apache.ibatis.builder.BuilderException: Error parsing Mapper XML. The XML location is 'com/zzxtit/boot/mybatis/mapper/stuMapper.xml'. Cause: org.apache.ibatis.builder.BuilderException: Error resolving class. Cause: org.apache.ibatis.type.TypeException: Could not resolve type alias 'student'. Cause: java.lang.ClassNotFoundException: Cannot find class: student
at org.apache.ibatis.builder.xml.XMLConfigBuilder.parseConfiguration(XMLConfigBuilder.java:121)
at org.apache.ibatis.builder.xml.XMLConfigBuilder.parse(XMLConfigBuilder.java:98)
at org.apache.ibatis.session.SqlSessionFactoryBuilder.build(SqlSessionFactoryBuilder.java:78)
... 25 more
Caused by: org.apache.ibatis.builder.BuilderException: Error parsing Mapper XML. The XML location is 'com/zzxtit/boot/mybatis/mapper/stuMapper.xml'. Cause: org.apache.ibatis.builder.BuilderException: Error resolving class. Cause: org.apache.ibatis.type.TypeException: Could not resolve type alias 'student'. Cause: java.lang.ClassNotFoundException: Cannot find class: student
at org.apache.ibatis.builder.xml.XMLMapperBuilder.configurationElement(XMLMapperBuilder.java:122)
at org.apache.ibatis.builder.xml.XMLMapperBuilder.parse(XMLMapperBuilder.java:94)
at org.apache.ibatis.builder.xml.XMLConfigBuilder.mapperElement(XMLConfigBuilder.java:373)
at org.apache.ibatis.builder.xml.XMLConfigBuilder.parseConfiguration(XMLConfigBuilder.java:119)
... 27 more
Caused by: org.apache.ibatis.builder.BuilderException: Error resolving class. Cause: org.apache.ibatis.type.TypeException: Could not resolve type alias 'student'. Cause: java.lang.ClassNotFoundException: Cannot find class: student
at org.apache.ibatis.builder.BaseBuilder.resolveClass(BaseBuilder.java:118)
at org.apache.ibatis.builder.xml.XMLMapperBuilder.resultMapElement(XMLMapperBuilder.java:266)
at org.apache.ibatis.builder.xml.XMLMapperBuilder.resultMapElement(XMLMapperBuilder.java:253)
at org.apache.ibatis.builder.xml.XMLMapperBuilder.resultMapElements(XMLMapperBuilder.java:245)
at org.apache.ibatis.builder.xml.XMLMapperBuilder.configurationElement(XMLMapperBuilder.java:118)
... 30 more
Caused by: org.apache.ibatis.type.TypeException: Could not resolve type alias 'student'. Cause: java.lang.ClassNotFoundException: Cannot find class: student
at org.apache.ibatis.type.TypeAliasRegistry.resolveAlias(TypeAliasRegistry.java:120)
at org.apache.ibatis.builder.BaseBuilder.resolveAlias(BaseBuilder.java:149)
at org.apache.ibatis.builder.BaseBuilder.resolveClass(BaseBuilder.java:116)
... 34 more
Caused by: java.lang.ClassNotFoundException: Cannot find class: student
at org.apache.ibatis.io.ClassLoaderWrapper.classForName(ClassLoaderWrapper.java:200)
at org.apache.ibatis.io.ClassLoaderWrapper.classForName(ClassLoaderWrapper.java:89)
at org.apache.ibatis.io.Resources.classForName(Resources.java:261)
at org.apache.ibatis.type.TypeAliasRegistry.resolveAlias(TypeAliasRegistry.java:116)
... 36 more
改正
<typeAliases>
<typeAlias alias="student" type="com.zzxtit.boot.mybatis.first.Student"/>
</typeAliases>